Plasticizing copolymers



v Patented Dec. 18, 1945 J UNITED STATES PATENT .OFFIGE PLASTICIZING QOPOLYMER-S Harry B. Thompson, Akron, Ohio, assignor to Wingtoot Corporation, Akron, Ohio, a corporation of Delaware v No Drawing. Application June 3, 1943, Serial No. 489,507

v 1 Claim. (01. zoo-sci This invention relates to plasticizing a copoly- The following example illustrates the invenmer of butadiene and styrene or butadiene and tion:

acrylonitrile. Such copolymers are well known Seventy-five pounds of ground, raw synthetic in the art, being rubber substitutes used in the -Buna S (a copolymer of butadiene and styrene) production of automobile tires, etc; 1 5 is placed onstandard rubber mixing rolls. Three According to this invention, the raw copolypounds of aceticacid are added after 1 minute of mer is plastlcized with a fatty acid-for examwarming up to 125 150150". F. The materials are ple, acetic acid, butyric acid, citric acid, lauric then mixed onthe. mm for about minutes.

acid or other aliphatic carboxylic acid,'such as when removed from the mill, the material is benzoic acidor it is plasticized with a mono- 10 ready for processing by standard rubber-workhydric alcohol, such as methyl alcohol, ethyl aling equipment. Instead of acetic acid, methyl 6 ,'P DY alcohol. butyl alcohol, Ordialcohol may be used. In employing an alcohol,

narily, one will not use an alcohol or acid conit is necessaryto see that thetemperature of taming more tha e t c b ns in the chain, the plastic does not-become so high that the and the chain will usually be saturated. alcohol i vaporized.

vThe Plasticizing operation is prefe a Buna N (butadiene and acrylonitrile) may be ried out on a rub mil Th raw c polym r. substituted for Buna s in the above formula. Pr fer bly t a som what e vat d temperature, It may be plasticized with either an alcohol or is worked on the mill until slightly warm. For a id as here described.

example, it may be heated to a temperature or This invention is in part a continuation of my l -15 F- The plasticizer 1 then added nd application Serial No. 435,131, flied March 18,

blended in'to'the copolymer. This is done by 1942.-

milling the two materials together fora number w t I claim is: Y

of minutes, for example, from about 8.to 15 An uncured, rubber-like copolymer of butadiminutes- .The am u t f plasticizer loy ene and styrene which contains between about will depend upon the degree of plasticity desired. 2% and about 8% based onthe weight of the At least 1 P nt O plflsticlzerwill be usedcopolymer 0! methyl alcohol as apl'asticizer. For example, from 2 to 6 per cent of acetic acid .or more may be used up to 10 per cent or higher.- 1 my 3. THOMPSON. 1! methyl alcohol is employed, from 2 to 8 per jQ I cent will generally be used. I 

